Inspiration-centric support Warlock.

If you are a Human Entertainer Warlock, you can have three origin feats at level one by grabbing Lessons of the Old Ones and taking the human's origin feat. By doing this, you can get Musician, Zhentarim Ruffian, and Tireless Reveler. At the end of every rest all the other characters in the party gain Heroic Inspiration, as do you on a long rest. At the start of combat, you can use Zhentarim Ruffian to give the whole party advantage on initiative by using your Heroic Inspiration. When your party members use their inspiration, you can use Tireless Reveler to regain your inspiration and be ready to start the next fight with advantage.
If your party likes to hoard Inspiration, you could take the Vestige patron and/or Pact of the Chain to get allies you can store inspiration from Musician in and they can expend their inspiration on random attack rolls or their save effects to provoke Tireless Reveler.
Thoughts on more ways to improve this combo?

Well, two things to keep in mind that limit this a bit:

1. Lessons of the First Ones isn't actually available until level 2. As far as I know there isn't currently a way to get three Origin Feats at level 1 in any official material.
2. Musician's inspiration benefit only works on a limited number (your Proficiency Bonus) of people at a time, so gathering more allies doesn't necessarily help that much.

As for improving it: the other big source of Heroic Inspiration is being a Champion Fighter. Once you reach level 10, you gain Heroic Inspiration at the start of every combat turn if you don't already have it. If you have Tireless Reveler, you really want someone else in the party to be a Champion, because they're probably going to get and use Heroic Inspiration almost every turn, so you'll almost always have an opportunity to use Tireless Reveler in a fight.

Something else to note is that there are a bunch of other Origin Feats that grant Heroic Inspiration for doing specific things: Arcane Artist, Arcane Undertaker, Cult of the Dragon Initiate, Lords' Alliance Agent, and Purple Dragon Rook. Most of these are once-per-Long-Rest kind of things, so they're not worth replacing any of the three you've mentioned, but they could be used to augment it a bit.

Quote from wagnarokkr >>

Musician's inspiration benefit only works on a limited number (your Proficiency Bonus) of people at a time, so gathering more allies doesn't necessarily help that much.

 

 I mean if your party doesn't use their inspiration between the rests, you could give the musician inspiration to the pets. That way everyone has inspiration for fuel.